Learning to deal with life's ups and downs

Abstract

A study shows that circadian glucocorticoid oscillations have dual roles in dendritic spine plasticity. Glucocorticoids control spine formation and elimination through distinct mechanisms, which together are important for motor learning and maintenance.

Figure 1

Two-photon in vivo imaging of the mouse motor cortex before and after motor learning on the rotarod task. Acquisition of learning requires an intact circadian peak and activation of glucocorticoid receptors (GR), which results in phosphorylation of cofilin and increased spine formation through a rapid, nontranscriptional mechanism. Retention of learning requires the circadian trough, leading to spine elimination through a transcriptional mechanism requiring activation of mineralocorticoid receptors (MR).